import pandas as pd
df=pd.DataFrame({'商品':['苹果','香蕉','梨'],
                 '单价(元)':['5','5','4'],
                 '销量(kg)':['100','None','None'],
                 '库存(kg)':['50','None','70']})
print('原始数据: \n', df)
print('删除包含缺失值的行: \n', df.dropna())
print('删除包含缺失值的列: \n', df.dropna(axis=1))
print('删除少于3个非缺失值的行: \n', df.dropna(thresh=3))
print('删除库存列包含缺失值的行: \n', df.dropna(subset=['库存(kg)']))